Chapter 4 - Summary¶

Chapter 4 included the following concepts from computing.

Append - You can add two strings together using the + symbol. This is also called concatenate.
Capitalize - The capitalize function returns a new string with the first character capitalized.
Concatenate - You can use + to concatenate (append) two strings like this string3 = string1 + string2. This will create a new string called string3 with all the characters from the first string, string1, followed by all the characters in the second string, string2.
Function - A function returns a value. Function can take input as well, but don’t have to. An example is the string lower() function that returns a string with all lowercase letters.
Immutable - Immutable means that it does not change. Strings are immutable in Python. When you call a function that appears to change a string, it will actually return a new string.
Index - An index is a number associated with the position of a character in a string. In Python the first character in a string is at index 0.
Input - Data fed into a computing process. In python, the input function can be used to get data from users.
Object - An object can have behavior (things it can do). For example a turtle object can go forward a specified amount. Strings and turtles are objects in Python.
String - A string is a sequence of characters. You specify a string as characters inside a pair of single, double, or triple quotes.
Substring - A substring is a part of a string. One substring of “Hi there” would be “Hi”.

Summary of String Functions¶

Chapter 4 also included the following string functions.

append - You can add two strings together using the + symbol. This is also called concatenate. The result of "Happy" + " Birthday" is "Happy Birthday".
find - The find function takes a string as input and returns the index of the first occurence of that string in the string the function is called on. The code "goodbye".find('bye') returns 4.
len - The len function that can take a string as input and returns the number of characters in the string including any spaces. For example len("Hi there") will return 8.
lower - The lower string function returns a new string with only lowercase letters. For example "ALL CAPS".lower() returns "all caps".
input - The input function returns a string from the user. It can also print out a message to the user, called a prompt.
slice - You can get part of a string which is also called a substring using [start] or [start:end] which will return a substring of the current string starting at the given start position and if an end position is given ending at the character before the end position. For example "out"[1] will return "u" and "otter"[2:5] returns "ter".

Next Section - Chapter 4 Exercises